[Research on the association between unhealthy lifestyle and psychological distress among Chinese children and adolescents aged 9-18 years]

Objective: To evaluate the level of psychological distress among Chinese children and adolescents and analyze its lifestyle influencing factors. Methods: Data were obtained from the 2019 Chinese National Survey on Students' Constitution and Health. A lotal of 120 285 Han Chinese children and adolescents aged 9-18 years with complete information on the psychological distress scale and lifestyle factors were selected, including 58 432 boys and 61 853 girls. The Kessler Psychological Distress Scale (K10) measured psychological distress, and lifestyles such as physical activity, sedentary behavior, diet, and sleep were also investigated. K10 scores of different genders were compared using the t-test, and the levels of psychological distress were compared using the χ2 test. Logistic regression was used to analyze lifestyle risk factors associated with high psychological distress, and multiple linear regression was used to find the relationship between K10 scores and lifestyle scores. Results: The average K10 score for Han Chinese children and adolescents aged 9-18 years was 21.25±7.35, with girls (21.43±7.35) scoring higher than boys (21.06±7.36), the difference was statistically significant (t=8.72, P<0.001). The rate of high psychological distress was 29.81%, with girls (31.08%) reporting higher rates than boys (28.46%), the difference was statistically significant (χ2=98.54,P<0.001). 56.10% of children and adolescents have unhealthy lifestyles, with girls (58.77%) reporting higher rates than boys (53.27%), the difference was statistically significant (χ2=368.53,P<0.001). Except for insufficient outdoor activities for girls (P=0.128), lifestyles such as insufficient physical activity, insufficient muscle-and-bone exercises, long screen time, not eating breakfast, eggs and dairy products every day, drinking sugary beverages once or more per day, and not having enough sleep are all risk factors for high psychological distress (all P<0.001). For every additional healthy lifestyle score, the K10 score decreased by 0.98 [β=-0.98 (95%CI: -1.01- -0.95)] points (P<0.001). K10 scores in each region negatively correlate with lifestyle scores (all P<0.001). Among them, the K10 score in the eastern region showed the slightest decrease as the lifestyle score increased, while the western region showed the most decrease. Conclusions: The prevalence of psychological distress and unhealthy lifestyle in Chinese children and adolescents are high and interrelated. Compared those with healthy lifestyles, children and adolescents with unhealthy lifestyles are at greater risk of high psychological distress. Therefore, promoting healthy lifestyles for children and adolescents may be one of the important ways to improve their mental health.

[Research on the association between the occurrence of spermarche and menarche and psychological distress among Chinese children and adolescents aged 9-18 years]

Objective: To analyze the association between the occurrence of spermarche and menarche and psychological distress among Chinese Han children and adolescents aged 9 to 18 years. Methods: Data were drawn from the 2019 Chinese National Survey on Students' Constitution and Health, and a total of 54 438 boys aged 11 to 18 years and 76 376 girls aged 9 to 18 years with psychological distress, spermarche/menarche records were included in the final analysis. The occurrence of spermarche/menarche was recorded by physicians, and psychological distress was classified according to the Kessler Psychological Distress Scale scores. The chi-square test was used to compare the difference between groups in the occurrence of spermarche/menarche, and the multinomial logistic regression model and stratification analysis was established to analyze the association between psychological distress and spermarche/menarche. Results: The incidence of spermarche/menarche in 2019 ranged from 6.3% to 96.5% for eight age groups of Chinese boys and 2.8% to 99.0% for ten age groups of girls. The rates of high psychological distress among boys and girls were 32.5% and 32.7%. Among boys aged 11 to 18 years, the rate of high psychological distress increased with age, with a trend test P<0.001, and the difference in the rate of high psychological distress between those who had and had not had their spermarche was not statistically significant in all age groups. Among girls aged 9 to 18 years, the rate of high psychological distress increased with age, with a trend P<0.001; the rate of high psychological distress was higher in the group with menarche at age 10 and 12 than in the group without menarche (all P<0.05). High psychological distress was positively correlated with spermarche among boys aged 13-15 years living in urban areas and hight level economic development areas (OR=1.11, 95%CI: 1.02-1.21;OR=1.18, 95%CI: 1.06-1.32). Overall, high psychological distress was positively correlated with menarche in girls aged 9-12 and 13-15 years (OR=1.33, 95%CI: 1.25-1.42; OR=1.22, 95%CI: 1.07-1.39). High psychological distress was positively correlated with menarche among girls aged 9-12 years living in different regions except for the Northeast region, in areas with different levels of economic development, and in urban and rural areas, in girls aged 13-15 years living in urban, central, and western regions, and in girls aged 16-18 years residing in the central region. Conclusions: This study found an association between the occurrence of spermarche/menarche and psychological distress among Chinese Han children and adolescents aged 9 to 18 years in 2019, which was particularly significant among girls aged 9 to 12 years and boys aged 13 to 15 years living in areas with higher levels of socioeconomic development.

[Research on the association between the status of physical fitness and psychological distress among Chinese children and adolescents aged 13-18 years]

Objective: To describe the status of physical fitness of children and adolescents aged 13-18 years in China in 2019 and analyze its association with psychological distress. Methods: Data were drawn from the 2019 Chinese National Survey on Students' Constitution and Health, and 90 633 Han children and adolescents aged 13-18 years were included. Physical fitness was evaluated by "National Students Constitutional Health Standards" (2014 revised edition). Psychological distress was classified according to the scores of the Kessler Psychological Distress Scale: ≤19, 20-24, 25-29, and ≥30 scores indicated no, mild, moderate, and severe psychological distress, respectively, with moderate and severe psychological distress collectively referred to as high psychological distress. The χ2 test was used to compare the distribution differences between boys and girls, the Cochran-Armitage test was used to analyze the trend, and the multinomial logistic regression in the mixed effect model was established to analyze the association between physical fitness and psychological distress. Results: In 2019, the unqualified rate of physical fitness among children and adolescents aged 13-18 years in China was 17.2%, and the prevalence of excellent and good physical fitness was 18.2%, which was lower among boys (15.9%) than girls (20.5%) with a statistically significant difference (P<0.05). The excellent and good physical fitness rate showed a significantly decreasing trend with age (trend test P<0.05). The rate of high psychological distress among children and adolescents aged 13-18 years in China in 2019 was 39.3%, with boys (37.0%) having a lower prevalence than girls (41.6%), supported by a statistically significant difference (P<0.05), and a decreasing trend with the degree of physical fitness was observed both in boys and girls (trend test P<0.05). The multinomial logistic regression model showed that the prevalence of moderate (OR=0.83, 95%CI: 0.79-0.88, P<0.001) and severe (OR=0.81, 95%CI: 0.77-0.86, P<0.001) psychological distress were both lower in children and adolescents with excellent and good physical fitness. Conclusion: The status of physical fitness and psychological distress of Chinese children and adolescents aged 13-18 in 2019 was not optimistic, with physical fitness showing a significantly negative association with psychological distress.

[Prevalence of psychological distress among Chinese children and adolescents aged 9-18 years]

Objective: To describe the prevalence of psychological distress and to analyze its influencing factors among Chinese children and adolescents aged 9-18 years in 2019. Methods: Data was from the 2019 Chinese National Survey on Students' Constitution and Health, and 148 892 children and adolescents were included. Psychological distress was measured using the Kessler Psychological Distress Scale (K10): scores ≤19 were defined as no psychological distress, scores between 20-24 were defined as mild psychological distress, scores between 25-29 were defined as moderate psychological distress, and scores ≥30 were defined as severe psychological distress (moderate to severe psychological distress were defined as high psychological distress). The ANOVA, t test, and χ2 test were used to compare the differences in K10 scores and high psychological distress rates among children and adolescents with different characteristics. The ANOVA and trend χ2 test were used to analyze the trends. Modified-Poisson regression models were used to determine influencing factors of high psychological distress. Results: The K10 scores for Chinese children and adolescents aged 9-18 years in 2019 was 21.5±9.2, and their rate of high psychological distress was 31.6%. The rates of high psychological distress among children and adolescents aged 9-12, 13-15, and 16-18 years were 22.3%, 35.9%, and 38.8%. K10 scores and rates of high psychological distress showed an increasing trend as age increased (trends test all P<0.001). K10 scores and rates of high psychological distress were higher among children and adolescents who were older, female, rural, in areas with medium to low GDP per capita level, and with lower parental education (all P<0.001). Multifactorial modified-Poisson regression analysis showed that children and adolescents aged 13-15 years, 16-18 years, female, rural, and in areas with low to moderate GDP per capita level were at higher risk of high psychological distress (all P<0.05), with aOR (95%CI) of 1.55 (1.52-1.58), 1.66 (1.63-1.69), 1.07 (1.05-1.09), 1.02 (1.01-1.04), 1.10 (1.07-1.12). Children and adolescents in areas with medium to high GDP per capita level, whose father had a secondary or high school degree, whose father had a college degree or above, whose mother had a secondary or high school degree, and whose mother had a college degree or above were at lower risk of high psychological distress (all P<0.05), with aOR (95%CI) of 0.96 (0.94-0.98), 0.92 (0.90-0.93), 0.84 (0.82-0.86), 0.95 (0.93-0.97), 0.86 (0.83-0.88). Conclusions: The prevalence of psychological distress was high among Chinese children and adolescents aged 9-18 years in 2019, which is a vital problem. Mental health interventions need to be implemented among children and adolescents that were older, girls, rural, live in areas with lower economic levels, and whose parents have a lower education level.

[Research on the association between ambient PM2.5 and its components and psychological distress among Chinese children and adolescents aged 9-18 years]

Objective: To analyze the association between exposure to ambient PM2.5 and its components [sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), organic matter (OM), and black carbon (BC)] and psychological distress among school children and adolescents aged 9 to 18 years in China. Methods: Based on data from the 2019 Chinese National Survey on Students' Constitution and Health, 130 808 children and adolescents aged 9 to 18 years were included. Scoring and determination of higher psychological distress were based on the Kessler Psychological Distress Scale (K10), and annual average exposure data for air pollution were matched by survey location and time. We used a restricted cubic spline approach based on logistic regression to fit the associations between PM2.5, SO42-, NO3-, NH4+, organic matter, black carbon concentrations, and psychological distress. Logistic regression models were used to analyse different age, gender, BMI and physical activity subgroups to estimate the association between exposure to high levels of pollution and high levels of psychological distress in different subgroups. Results: The proportion of children and adolescents with high levels of psychological distress in China was 30.4%, with girls being higher than boys at 31.6% and 29.1%, respectively (P<0.05). A non-linear positive association existed between exposure to PM2.5, SO42-, NO3- and organic matter concentrations and higher psychological distress. As PM2.5, NO3-, NH4+, organic matter, and black carbon concentrations continued to rise, the increase in the risk of higher psychological distress slowed, while SO42- showed little change in the OR of psychological distress at lower concentrations but continued to rise at higher concentrations. PM2.5 and its components were statistically associated with psychological distress in the physically inactive group but not in the physically active group. The association between high levels of pollutants and high psychological distress was stronger among students aged 9 to 12 years compared with students aged 13 to 15 years and 16 to 18 years. Conclusions: The ambient pollutant PM2.5 and its components are associated with psychological distress in children and adolescents aged 9 to 18 years in China. High pollutant exposure is a risk factor for high psychological distress among physically inactive children and adolescents, and there are age differences in the association between PM2.5 and components and psychological distress.

[Research on the association between overweight and obesity mediated by Chinese children and adolescent aged 13-18 years physical exercise and psychological distress]

Objective: To analyze the association between overweight and obesity, psychological distress, and the influence of physical exercise among Chinese children and adolescents. Methods: The study used data from the 2019 Chinese National Survey on Students' Constitution and Health. A total of 95 280 Han Chinese children and adolescents aged 13 to 18 years were included in the study based on complete information on overweight and obesity, psychological distress assessment, and physical exercise variables. The Kessler Psychological Distress Scale was used to measure their psychological distress, with scores above 25 indicating high psychological distress. The BMI group of the adolescents was evaluated according to the Chinese standard "WS/T 586-2018 Screening for Overweight and Obesity in School-age Children and Adolescents", including underweight, normal weight, overweight, and obesity. The individual's BMI Z-score (BMIZ) was evaluated using the WHO standard and divided into ten groups based on the population percentile distribution. The survey collected the subjects' average daily physical exercise time and divided them into two groups: less than 1 hour and greater than or equal to 1 hour. Logistic regression analysis was used to analyze the relationship between overweight and obesity and high psychological distress among children and adolescents and the differences in association between different physical exercise groups. Results: The detection rates of overweight and obesity among Han Chinese children and adolescents aged 13 to 18 years in 2019 were 14.5%, and 7.6%, respectively. The rate of high psychological distress was 37.6%, and the rate of average daily physical exercise time exceeding 1 hour was 17.1%. Using the population with a BMIZ P10 below as a reference, the association strength between high psychological distress and the population gradually increased, with an OR (95%CI) value of 1.08 (1.02-1.14), 1.09 (1.02-1.14), 1.10 (1.03-1.16), and 1.16 (1.09-1.23) for BMIZ in the P60-, P70-, P80-, >P90 groups. Compared to normal weight, both overweight and obesity were positively associated with high psychological distress in children and adolescents, with obesity showing a more significant correlation, while underweight was negatively associated with high psychological distress. The detection rates of high psychological distress in normal weight, underweight, overweight, and obese groups were 37.6%, 37.0%, 38.2%, and 38.7%, respectively, with an OR (95%CI) value of 0.93 (0.88-0.98) for the underweight group and 1.05 (1.01-1.10) and 1.13 (1.07-1.19) for the overweight and obese groups, respectively. The positive correlation between BMIZ, overweight, and obesity with high psychological distress was significant only in adolescents who exercised less than 1 hour per day on average. Conclusions: Chinese children and adolescents face the problem of obesity and high psychological distress, with a positive correlation between these two problems. Physical activity may moderate the association between obesity and psychological distress in children and adolescents. Adequate physical exercise may offset the potential high psychological distress caused by obesity in children and adolescents. Thus, strengthening physical exercise among children and adolescents reduces the risks of both obesity and psychological health problems effectively.

[Association of body fat distribution with depression and social anxiety in children and adolescents: A cross-sectional study based on dual-energy X-ray detection]

OBJECTIVE

To investigate the status of depression and social anxiety in children and adolescents, and to analyze the association between body fat distribution and depression, social anxiety in children and adolescents.

METHODS

A total of 1 412 children aged 7 to 18 years in Beijing were included by stratified cluster random sampling method. Body fat distribution, including total body fat percentage (total BF%), Android BF%, Gynoid BF% and Android-to-Gynoid fat ratio (AOI), were obtained by dual-energy X-ray absorption method. Depression and social anxiety were evaluated by Children Depression Inventory and Social Anxiety Scale for Children. Multivariate linear regression and restricted cubic spline analysis were used to estimate the linear and non-linear correlation between body fat distribution and depression and social anxiety.

RESULTS

13.1% and 31.1% of the children and adolescents had depressive symptoms and social anxiety symptoms respectively, and the detection rate of depression and social anxiety in the boys and young groups was significantly lower than those in the girls and old groups. There was no significant linear correlation between total BF%, Android BF%, Gynoid BF%, AOI and depression and social anxiety in the children and adolescents. However, total BF% and Gynoid BF% had significant nonlinear correlation with depression, showing an inverted U-shaped curve relationship with the tangent points of 26.8% and 30.9%, respectively. In terms of the nonlinear association of total BF%, Android BF%, Gynoid BF% and AOI with depression and social anxiety, the change trends of the boys and girls, low age group and high age group were consistent. The overall anxiety risk HR of body fat distribution in the boys was significantly higher than that in the girls, and the risk HR of depression and social anxiety were significantly higher in the high age group than those in the low age group.

CONCLUSION

There was no significant linear correlation between body fat distribution and depression and social anxiety in children and adolescents. Total BF% and depression showed an inverted U-shaped curve, mainly manifested in Gynoid BF%, and this trend was consistent in different genders and different age groups. Maintaining children and adolescents' body fat distribution at an appropriate level is the future direction of the prevention and control of depression and social anxiety in children and adolescents.

[Trend of age of menarche among Chinese Han girls aged 9 to 18 years from 2010 to 2019]

Objective: To analyze the trends of the age of menarche among Chinese Han girls aged 9 to 18 years from 2010 to 2019. Methods: Data were extracted from the Chinese National Surveys on Students' Constitution and Health in 2010, 2014 and 2019. A total of 253 037 Han girls aged 9 to 18 years with complete data on menarche were selected in this study. They were asked one-on-one about their menstrual status, age and residence information. The median age of menarche was estimated by probability regression. U tests were used to compare the difference in median age at menarche in different years. Results: The median age at menarche (95%CI) among Chinese Han girls was 12.47 (12.09-12.83) years in 2010, 12.17 (11.95-12.38) years in 2014 and 12.05 (10.82-13.08) years in 2019, respectively. Compared with that in 2010, the median age at menarche in 2019 decreased by 0.42 years (U=-77.27, P<0.001). The annual average changes were -0.076 years from 2010 to 2014 (U=-57.19, P<0.001) and -0.023 years from 2014 to 2019 (U=-21.41, P<0.001), respectively. The average annual changes in urban areas in the periods of 2010 to 2014 and 2014 to 2019 were -0.071 years and 0.006 years, respectively, while those in rural areas were -0.082 years and -0.053 years, respectively. The average annual changes in the regions of north, northeast, east, south central, southwest and northwest were -0.064, -0.099, -0.091, -0.080, -0.096 and -0.041 years in the period of 2010 to 2014 and 0.001, -0.040, -0.002, -0.005, -0.043 and -0.081 years in the period of 2014 to 2019. Conclusion: The age of menarche among Chinese Han girls aged 9 to 18 years shows an advanced trend from 2010 to 2019, and the trends in urban and rural areas and different regions have different characteristics.

[Perceived exercise benefits and barriers and their association with physical activity time in Chinese Han children and adolescents aged 9 to 18 years]

Objective: To analyze the perceived exercise benefits and barriers and their association with physical activity time in Chinese Han children and adolescents aged 9-18 years. Methods: Data were extracted from the 2019 Chinese National Survey on Students' Constitution and Health and a total of 163 656 children and adolescents aged 9-18 years in Han ethnic group were included in the analysis. Mann-Whitney U test and Kruskal-Wallis test were used to compare the perceived exercise benefits score, perceived exercise barriers score and perceived exercise benefits to barriers ratio in the children and adolescents with different demographic characteristics and physical activity time. The differences in physical activity time in subgroups were compared with χ² tests. log-binomial regression model was used to evaluate the association between physical activity time and perceived exercise benefits and barriers. Results: The M (Q₁,Q₃) of the perceived exercise benefits score, perceived exercise barriers score, and perceived exercise benefits to barriers ratio in the children and adolescents were 4.11 (3.78, 4.78), 2.70 (2.10, 3.20) and 1.55 (1.22, 2.07), respectively. Children and adolescents living in urban area, boys, those at younger age and those with physical activity time ≥1 hour had higher perceived exercise benefits score and perceived exercise benefits to barriers ratio, but lower perceived exercise barriers score (all P<0.001). The prevalence of physical activity time ≥1 hour was 41.4% in the children and adolescents. In the log-binomial model with two variables of perceived exercise benefits score and perceived exercise barriers score, for each 1-point increase in the perceived exercise benefits, the possibility of physical activity time ≥1 hour increased by 11% (OR=1.11, 95%CI: 1.10-1.12), and for each 1-point increase in the perceived exercise barriers, the possibility of physical activity time ≥1 hour decreased by 15% (OR=0.85, 95%CI: 0.84-0.85). In the log-binomial model with variable of perceived exercise benefits to barriers ratio, for each 1-point increase in the perceived exercise benefits to barriers ratio, the possibility of physical activity time ≥1 hour increased by 12% (OR=1.12, 95%CI: 1.11-1.12). Conclusion: The perceived exercise benefits and barriers are significantly associated with physical activity time in children and adolescents in China.

[Epidemiology and prediction of overweight and obesity among children and adolescents aged 7-18 years in China from 1985 to 2019]

Objective: To analyze and predict the epidemic trend of overweight and obesity among children and adolescents aged 7-18 years in China from 1985 to 2019. Methods: Data were collected from the Chinese National Survey on Students Constitution and Health in 1985, 1995, 2000, 2005, 2010, 2014, and 2019 with the sample size of 409 945, 204 931, 209 209, 234 420, 215 317, 214 353, and 212 711, respectively. Overweight and obesity were evaluated according to the "classification standard of the weight index value of overweight and obesity screening for Chinese school-age children and adolescents" of the Working Group on Obesity in China (WGOC). The detection rate and average annual growth rate of overweight and obesity, and single obesity among children and adolescents aged 7-18 years were calculated, and ArcGis10.6 software was used to analyze the difference in the prevalence of overweight and obesity among children and adolescents in different regions in 2019. Polynomial regression function was used to fit the prevalence and average annual growth rate of overweight and obesity, and single obesity among children and adolescents from 1985 to 2019, and to predict the prevalence of overweight and obesity and single obesity among children and adolescents in China. Results: In 2019, the total prevalence of overweight and obesity among children and adolescents aged 7-18 years in China was 23.4%, and the prevalence of single obesity was 9.6%. The prevalence of overweight and obesity among urban children and adolescents was higher than that in rural areas (25.4% vs. 21.5%), and the prevalence in boys was higher than that in girls (28.4% vs. 18.4%) (both P values<0.001). In 2019, there was a large regional disparity in the prevalence of overweight and obesity in different provinces, with the lowest in Guangdong (12.2%) and the highest in Shandong (38.9%), and the high epidemic areas were mainly concentrated in North China and Northeast China. From 1985 to 2019, the prevalence of overweight and obesity among children and adolescents aged 7-18 years in China increased from 1.2% to 23.4%, with an increase of 18.1 times, while the prevalence of obesity alone increased from 0.1% to 9.6%, with an increase of 75.6 times. The prevalence of overweight and obesity in urban boys, urban girls, rural boys and rural girls increased from 1.3%, 1.5%, 0.5%, and 1.6% in 1985 to 31.2%, 19.4%, 25.6%, and 17.4% in 2019, with an increase of 22.3, 11.7, 54.2, and 10.1 times, respectively. According to the prediction model, the prevalence of overweight and obesity among children and adolescents aged 7-18 years in China will increase from 23.4% in 2019 to 32.7% in 2030, and the prevalence of obesity alone will increase from 9.6% in 2019 to 15.1% in 2030. The growth of rural children and adolescents is obvious. By 2025, the prevalence of overweight and obesity among rural children and adolescents in China will comprehensively exceed that of urban, and there will be an "urban-rural reversal" phenomenon. At the same time, the prevalence of children's obesity in China's low, medium and high epidemic areas will also continue to increase. By 2035, the prevalence of overweight and obesity among children and adolescents in medium epidemic areas will exceed that in high epidemic areas, and there will be a "provincial reversal" phenomenon. Conclusion: From 1985 to 2019, the overweight and obesity of children and adolescents in China will continue to grow rapidly with large regional differences.

[Prevalence trend of malnutrition among Chinese Han children and adolescents aged 7-18 years from 2010 to 2019]

Objective: To analyze the prevalence trend of malnutrition among Chinese Han children and adolescents aged 7-18 years from 2010 to 2019. Methods: Based on the data from the Chinese National Surveys on Students' Constitution and Health in 2010, 2014 and 2019, about 215 102, 214 268 and 212 713 Han students aged 7-18 years were included in this study. According to the National Screening Standard for Malnutrition of School-age Children and Adolescents, the detection rate of malnutrition among Chinese Han children and adolescents aged 7-18 was calculated, and the prevalence trend of malnutrition from 2010 to 2019 was analyzed. Results: In 2019, the detection rate of malnutrition among Chinese Han students aged 7-18 years was 8.64% (18 381/212 713), of which the rate of growth retardation, moderate-to-severe wasting and mild wasting was 0.50% (1 062/212 713), 3.25% (6 914/212 713) and 4.89% (10 405/212 713), respectively. In 2019, the detection rate of malnutrition in these boys was higher than that of girls (9.97% vs. 7.31%), and the detection rate in rural areas was higher than that in cities (9.30% vs. 7.98%). The detection rates were 9.74% (5 252/53 916), 8.17% (4 408/53 937), 7.29% (3 885/53 310), and 9.38% (4 836/51 550) in 7-9, 10-12, 13-15, and 16-18 years groups, and 8.14% (6 563/80 618), 7.61% (4 237/55 694) and 9.92% (7 581/76 401) in the eastern, central, and western regions. Malnutrition among students in China was mainly caused by mild wasting, and the detection rate of growth retardation accounted for only 5.78% (1 062/18 381). Malnutrition was mostly concentrated in the southwest region, and the rate was relatively low in eastern provinces. In three surveys from 2010 to 2019, the detection rate of malnutrition among Han students aged 7-18 in China decreased gradually, and the differences were statistically significant (P<0.05). Among them, the detection rates in western rural areas decreased significantly, as well as the gap between urban and rural areas. Compared with that in 2014, the detection rate of malnutrition in Shandong, Hunan, Qinghai and Hainan provinces in 2019 decreased significantly (P<0.05). Conclusion: In 2019, the malnutrition of Chinese children and adolescents aged 7-18 years is dominated by wasting malnutrition. The detection rate shows a downward trend from 2010 to 2019, with regional differences.

[Trends of age of menarche among Chinese Han girls aged 9 to 18 years from 2010 to 2019]

Objective: To analyze the trends of the age of menarche among Chinese Han girls aged 9 to 18 years from 2010 to 2019. Methods: Data were extracted from the Chinese National Surveys on Students' Constitution and Health in 2010, 2014 and 2019. A total of 253 037 Han girls aged 9 to 18 years with complete data on menarche were selected in this study. They were asked one-on-one about their menstrual status, age and residence information. The median age of menarche was estimated by probability regression. U tests were used to compare the difference in median age at menarche in different years. Results: The median age at menarche (95%CI) among Chinese Han girls was 12.47 (12.09-12.83) years in 2010, 12.17 (11.95-12.38) years in 2014 and 12.05 (10.82-13.08) years in 2019, respectively. Compared with that in 2010, the median age at menarche in 2019 decreased by 0.42 years (U=-77.27, P<0.001). The annual average changes were-0.076 years from 2010 to 2014 (U=-57.19, P<0.001) and-0.023 years from 2014 to 2019 (U=-21.41, P<0.001), respectively. The average annual changes in urban areas in the periods of 2010 to 2014 and 2014 to 2019 were-0.071 years and 0.006 years, respectively, while those in rural areas were-0.082 years and-0.053 years, respectively. The average annual changes in the regions of north, northeast, east, south central, southwest and northwest were-0.064, -0.099, -0.091, -0.080, -0.096 and-0.041 years in the period of 2010 to 2014 and 0.001, -0.040, -0.002, -0.005, -0.043 and-0.081 years in the period of 2014 to 2019. Conclusion: The age of menarche among Chinese Han girls aged 9 to 18 years shows an advanced trend from 2010 to 2019, and the trends in urban and rural areas and different regions have different characteristics.

[Trend of the detection rate of myopia among Chinese Han children and adolescents aged 7-18 years from 2010 to 2019]

Objective: To analyze the trend of the detection rate of myopia among Chinese Han children and adolescents aged 7-18 years from 2010 to 2019. Methods: Data from the Chinese National Survey on Students' Constitution and Health in 2010, 2014 and 2019 were used, and about 213 833, 212 742 and 209 942 Han students aged 7-18 years were included in this study. The χ² test was used to compare the differences in the prevalence of myopia among the subgroups in the survey year, and logistic regression was used to compare the differences in the prevalence of myopia between different years. A curve-fitting method was used to obtain the growth rate of myopia among Han Chinese students from 2010 to 2019, and the differences in the change of myopia between different age groups were analyzed. Results: In 2019, the overall detection rate of myopia among Chinese Han children and adolescents aged 7-18 was 60.1%. The detection rate of urban students (62.7%) was higher than that of rural students (57.4%) and the detection rate of girls (63.5%) was higher than that of boys (56.7%). In 2019, the regional disparities were large in the detection rate of myopia in various provinces, with the lowest in Guizhou (49.6%) and the highest in Zhejiang (71.3%). The detection rate of myopia showed an upward trend from 2010 to 2019, from 55.5% in 2010 to 57.1% in 2014, and finally to 60.1% in 2019. The gap in the detection rate of myopia between urban and rural children and adolescents gradually shrank. The average annual growth rate of myopia detection rate from 2014 to 2019 was 0.6 percentage points per year, higher than that from 2010 to 2014 about 0.4 percentage points per year. The peak age of the growth rate of myopia detection rate decreased from 12 years in 2010 to 10 years in 2014, and finally to 7 years in 2019. Conclusions: The detection rate of myopia among Chinese Han children and adolescents is still at a high level, and the peak age of the growth rate of myopia detection rate continues to advance.

[Long-term trend of the age of spermarche and its association with nutritional status among Chinese Han boys aged 11-18 from 2010 to 2019]

Objective: To analyze the long-term trend of the age of spermarche among Chinese Han boys aged 11 to 18 from 2010 to 2019 and its association with nutritional status. Methods: The data from Chinese National Surveys on Students' Constitution and Health in 2010, 2014 and 2019 were used. The age, residence and spermarche of the participants were collected by questionnaire, and their height and weight were measured. A total of 184 633 Han boys aged 11‒18 years with complete data on spermarche, height, and weight were included in this study. The probability regression method was used to calculate the median age (95%CI) at spermarche in different areas, and the trend of age at spermarche in different groups was compared. The multivariate logistic regression model was used to analyze the association between nutritional status and spermarche of Chinese Han boys aged 11‒18 years. Results: The median age of spermarche (95%CI) was 13.85 (13.45-14.22) years old among Chinese Han boys aged 11‒18 years in 2019, with 0.18 years earlier than that in 2010. The median age at spermarche in urban and rural boys was 13.89 and 13.81 years, respectively. Compared with that in 2010, the age at spermarche in urban and rural boys was 0.08 and 0.27 years earlier, respectively. After adjusting for age, province and urban/rural areas, compared with normal weight, spermarche was negatively associated with wasting and positively associated with overweight and obesity, with OR (95%CI) about 0.73 (0.67-0.80), 1.09 (1.02-1.17) and 1.09 (1.01-1.18), respectively. Conclusion: The age of spermarche generally shows an advanced trend among Chinese Han boys and is associated with nutritional status.

[Prevalence trend of high normal blood pressure and elevated blood pressure in Chinese Han children and adolescents aged 7-17 years from 2010 to 2019]

Objective: To investigate the prevalence trend of high normal blood pressure and elevated blood pressure in children and adolescents aged 7 to 17 years in China from 2010 to 2019. Methods: Students aged 7-17 years were selected from the Chinese National Survey on Students' Constitution and Health from 2010 to 2019. High normal blood pressure and elevated blood pressure were determined according to the "Reference of screening for elevated blood pressure among children and adolescents aged 7-18 years" (WS/T 610-2018). The Chi-square test was performed to determine whether there was a difference in the prevalence of high normal blood pressure and elevated blood pressure by gender, residence and age group. Results: In 2019, the prevalence of high normal blood pressure in children and adolescents aged 7-17 years was 15.3% (29 855/195 625), which was higher in boys (20.2%, 19 779/97 847) and rural areas (15.4%, 15 066/97 567) than that in girls (10.3%, 10 076/97 778) and urban areas (15.1%, 14 789/98 058), respectively (all P<0.05). The prevalence of elevated blood pressure was 13.0% (25 377/195 625), which was higher in girls (13.2%, 12 925/97 778) and rural areas (14.1%, 13 753/97 567) than that in boys (12.7%, 12 452/97 847) and urban areas (11.9%, 11 624/98 058) (all P<0.05). From 2010 to 2019, the prevalence of high normal blood pressure showed an increasing trend, with an annual average growth rate from 1.14% to 3.18%. The overall prevalence of elevated blood pressure also showed an increasing trend from 2010 to 2019 but decreased in 2014. The annual average growth rate of elevated blood pressure was-1.07% from 2010 to 2014 and 9.33% from 2014 to 2019. About 17 provinces had an increasing trend in the prevalence of elevated blood pressure from 2010 to 2014, and 22 provinces with an increasing trend from 2014 to 2019. There were obvious regional differences in the annual average growth rate of the prevalence of high normal blood pressure and elevated blood pressure. The regions with the highest annual average growth rate of the prevalence of high normal blood pressure were the Northeast (5.47%) from 2010 to 2014 and the Western region (5.21%) from 2014 to 2019. For elevated blood pressure, the Northeast had the highest annual average growth rate from 2010 to 2014 (12.35%), while the Central (15.79%) and Western (12.87%) had the highest growth rate from 2014 to 2019. Conclusion: From 2010 to 2019, the prevalence of high normal blood pressure and elevated blood pressure in Chinese Han children and adolescents aged 7 to 17 shows an increasing trend, with regional disparities.

[Prevalence of unhealthy lifestyle among children and adolescents of Han nationality in China]

Objective: To explore the epidemiological characteristics and geographical distribution of unhealthy lifestyle among children and adolescents of Han nationality in China and obtain evidence for proposing the related strategies to improve the well-being of this population. Methods: Students aged 6-22 years old were selected from the Chinese National Survey on Students Constitution and Health in 2019. The prevalence of unhealthy lifestyles (physical inactivity, lack of outdoor activity, sedentary behavior, excessive screen time, sleep insufficiency, unhealthy eating behavior) between sex, residence, and age groups was calculated and compared. Multilevel logistic regression was used to explore the influencing factors of unhealthy lifestyle. Results: The prevalence of moderate-to-vigorous physical activity less than 1 h/d or 30 min/d were 82.06% and 54.69%, respectively. The prevalence of less than 2 h/d or 3 h/d of outdoor activities were 95.20% and 83.26%, respectively. The prevalence of more than 2 h/d or 3 h/d of sitting time were 50.64% and 31.92%, respectively. The prevalence of more than 2 h/d or 3 h/d of screen time were 42.02% and 27.79%, respectively. The prevalence of sleep insufficiency, excessive sugary beverages consumption (≥ 1 time/d), and insufficient consumption of eggs, milk, and breakfast (<7 d/week) were 66.49%, 20.97%, 83.36%, 70.71%, and 34.34%, respectively. The prevalence of severe sleep insufficiency, excessive sugary beverages consumption (≥ 3 times/d), and insufficient consumption of eggs, milk, and breakfast (≤2 d/week) were 27.77%, 8.21%, 47.21%, 32.36% and 9.73%, respectively. Conclusion: In 2019, unhealthy lifestyle is common among Han students aged 6-22 years in China. It is of importance to propose policies to strengthen the health education and initiatives to support healthy behaviors in Han children and adolescents. Jointly promotion on the creation of a healthy environment for Han children and adolescents, and formulation of targeted improvement measures in accordance with the epidemic characteristics in various regions are essential to improve the healthy lifestyle of this population.

[Associations between early onset of puberty and obesity types in children: Based on both the cross-sectional study and cohort study]

OBJECTIVE

To explore and analyze the relationship between early onset of puberty and different types of obesity in children, by combining large sample cross-sectional survey data with long-term longitudinal cohort data, so as to provide clues for further clarifying the health hazards of early onset of puberty and obesity prevention and control.

METHODS

The research data were from the cross-sectional survey data of seven provinces(autonomous regions, municipalities) in China and the cohort data of adolescent development in Xiamen. The study first found the association between early onset of puberty and obesity by Logistic regression on the cross-sectional data, and then used Poisson regression to analyze the association between early puberty initiation and various types of obesity risk.

RESULTS

In the study, 43 137 and 1 266 children were included in the cross-sectional survey and cohort survey respectively. The cross-sectional study found that among the girls aged 10-13 years, compared with the girls of the same age who did not start puberty, the body mass index (BMI)-Z score of the girls in the puberty start group was 0.5-0.8 higher, and the waist circumference Z score was 0.4-0.7 higher, and the risk of various types of obesity was higher. At the same time, the early onset of puberty was positively correlated with simple obesity, central obesity and compound obesity, the OR (95%CI) were 1.86 (1.42-2.44), 1.95 (1.65-2.32) and 1.86 (1.41-2.45), respectively. No significant association was found in boys. According to the cohort data, in girls, the risk of simple obesity was 6.00 times [RR (95%CI): 6.00 (1.07-33.60)], the risk of central obesity was 3.30 times [RR (95%CI): 3.30 (1.22-8.92)], and the risk of compound obesity was 5.76 times [RR (95%CI): 5.76 (1.03-32.30)], compared with the group without early puberty initiation, while no association between early puberty initiation and obesity was found in boys.

CONCLUSION

Based on the cross-sectional survey and longitudinal cohort survey, it is confirmed that the early onset of puberty in girls may increase the risk of simple obesity, central obesity and compound obesity, while there is no significant correlation between puberty onset and obesity in boys.

[Effect of outdoor time on the incidence of myopia among primary school students in 9 provinces of China]

Objective: We aimed to assess the effects of outdoor time in preventing incident myopia among primary school students and evaluate its differences among different grades to provide evidence for policy formulation related to myopia prevention. Methods: This study is a cohort study. We investigated 6 046 grade 1 to 5 students in 9 provinces, Jiangsu, Shanghai, Fujian, Shanxi, Henan, Hunan, Gansu, Chongqing, and Guangxi. In 2019, we measured their myopia on site. In 2020, we did a follow-up visit on those students to detect the myopia incidence rate. Information regarding outdoor time and myopia-related behaviors were obtained from a questionnaire within one week of visual acuity measurement in 2020. The chi-square test and Cochran-Armitage trend test compared the differences between groups. The Cox proportional hazards risk model was used to test the relationship between outdoor time and myopia. Results: In 2020, the overall myopia incidence rate of grade 1 to 5 students in the baseline was 27.5%; while 23.0% in grades 1 and 2 students and 31.7% in grades 3 to 5 students, respectively. After controlling for covariates, for students in grade 1 to 2, those with ≥1 hour of outdoor time per day were at 0.76 (95%CI: 0.62-0.93, P=0.008) times risk of being myopia than that of students with <1 hour of outdoor time per day; while for students in grades 3 to 5, an average of ≥3 hours of outdoor time per day was required to have a significant protective effect on myopia. The students with ≥3 hours of outdoor time per day were less likely to be myopia (OR=0.75, 95%CI: 0.61-0.93, P=0.007) than those students with <3 hours of outdoor time per day. Conclusions: For grade 1 and 2 students, 1 hour of outdoor time per day could reduce the incidence of myopia, whereas for grade 3 to 5 students, 3 hours of outdoor time per day could effectively reduce the incidence of myopia. Therefore, the recommendations for outdoor time as myopia prevention should be different for different grades. The higher the grade is, the more outdoor time should be spent to reduce myopia incidence. Moreover, other factors that affect myopia's incidence should be also paid attention to, and a comprehensive approach should be adopted to prevent and control the incidence of myopia.

[Clinical study on the effects of neoadjuvant chemotherapy on lymph node ratio, prognosis, and survival analysis of stage ⅢA-N2 non-small cell lung cancer]

Objective: To investigate the effect of neoadjuvant chemotherapy (NCT) on the lymph node ratio (LNR) of patients with stage ⅢA-N2 non-small cell lung cancer (NSCLC), and analyze the relationship between LNR and prognosis. Methods: The data of 128 patients with stage ⅢA-N2 NSCLC admitted to the Department of Cardiothoracic Surgery of the First Affiliated Hospital of Hebei North University from January 2013 to December 2018 were retrospectively collected. The patients were divided into two groups according to the treatment method. The patients in the observation group (64 cases) were treated with NCT and surgery, and the patients in the control group (64 cases) were treated with surgery. Lymph node metastasis and survival were observed in the two groups. Subgroups were divided according to LNR and N2 lymph node status, and survival analysis was performed for each subgroup. Univariate and multivariate analysis were conducted for the observation group. Results: The number of metastatic lymph nodes, the proportion of patients with positive lymph nodes, and the rate of lymph node metastasis in the observation group were lower than those in the control group,3.8±2.1 vs 4.9±2.4,92.2% vs 100%,19.1% vs 22.4% respectively (all P<0.05). Progression-free survival (PFS) and overall survival (OS) in the observation group were better than those in the control group (both P<0.05). Both the observation and control subgroups with low LNR had better PFS and OS than the subgroups with high LNR (both P<0.05). Patients in the observation group with non-multi-site N2 lymph node metastasis had better PFS and OS (both P<0.05). Univariate analysis of observation group showed that patients with low LNR had better 2-year PFS and OS(both P<0.05). Multivariate analysis showed that the higher the LNR, the greater the risk of death (HR=2.178,95%CI: 1.025-4.626,P=0.043) and progression (HR=2.130,95%CI: 1.123-4.038,P=0.021). Conclusion: NTC could improve the prognosis and reduce LNR of patients with stage ⅢA-N2 NSCLC, and LNR was expected to be a prognostic indicator.

[Association between endurance quality and blood pressure levels in Han students aged 13-18 years in China, 2014]

Objective: To analyze the association between the endurance quality and blood pressure levels in Han students aged 13-18 years in China. Methods: We used the data of Han students aged 13-18 years from 2014 Chinese National Survey on Students' Constitution and Health. Elevated blood pressure and its components, including isolated elevated SBP, isolated elevated DBP, and mix elevated blood pressure, were evaluated according to the reference of screening for elevated blood pressure among children and adolescents aged 7-18 years. The students' endurance quality was scored according to the National Standards for Students' Physical Health (2014 revision) and categorized based on their percentiles into four groups as follows: P(0)-, P(25)-, P(50)-, and P(75)-P(100). Trend χ(2) test was used to analyze the trend of the detection rates of elevated blood pressure and its components in different groups of endurance quality. Logistic regression model was used to estimate the odds ratio (OR) for elevated blood pressure and its components in different endurance quality groups and P(0)-group was set as reference group. Quantile regression model was used to analyze the association between different blood pressure levels and endurance quality. Results: The detection rate of elevated blood pressure in the students aged 13-18 years in China in 2014 was 9.2%. The detection rate of elevated blood pressure and its components decreased with the improvement of endurance quality (P<0.001). With the P(0)-endurance quality group as reference, the OR(95%CI) were 0.89(0.84-0.95), 0.81(0.76-0.86) and 0.79(0.74-0.84) respectively in P(25)-, P(50)- and P(75)-P(100) endurance quality groups respectively. The negative association existed between endurance quality and elevated blood pressure in overweight, obese and normal students, but not in malnourished students. The quantile regression analysis results showed that in overweight and obese students, the SBP levels at the P(10), P(25), P(50), P(75), P(9)0 and P(95) groups were negatively associated with the endurance quality, and the DBP levels at the P(25) and above group were negatively associated with the endurance quality. In malnourished and normal students, only some levels of DBP were negatively associated with the endurance quality. Conclusions: The negative association existed between endurance quality and elevated blood pressure in Han students aged 13-18 years in China. In overweight and obese students, the association between endurance quality and blood pressure level was stronger. Improving students' endurance quality may facilitate the prevention of elevated blood pressure.

[Surgical strategy of intraspinal tumors using minimal invasive channels]

Objective: To compare and analyze the effect of minimally invasive surgery and traditional open surgery in patients with spinal canal tumors, including intraspinal and extraspinal communication tumors. Methods: From 2017 to 2019, 31 patients (minimally invasive channel group) were included in the neurosurgery department of Huashan Hospital Affiliated to Fudan University, and 38 patients (open operation group) were selected as the control group. From the aspects of intraoperative condition, operative effect, postoperative muscle injury, postoperative complications, postoperative spinal stability, the minimally invasive access group and the open operation group were compared and analyzed. Results: The bleeding volume (70.2 ml±4.9 ml), operation time (164.7 min±16.0 min) and hospitalization days (9.5±2.5) in the minimally invasive access group were significantly lower than those in the open operation group (P<0.001). The creatine kinase CK (363.9 U/L±51.6 U/L) in the minimally invasive group was significantly lower than that in the open group (514.2 U/L±68.3 U/L) (P<0.001). According to Panjabi standard, the effect of spinal cord stability in minimally invasive group was significantly lower than that in open operation group (P<0.001), and the symptom improvement rate in minimally invasive group was significantly higher than that in open hand group (P<0.05). Conclusions: Compared with the open surgery, the amount of bleeding, the length of incision, the time of operation and the days of hospitalization were significantly shorter, the degree of muscle damage was also significantly reduced, the incidence of complications was lower, the impact of spinal stability was smaller, and the overall advantage was obvious.

Association of Chemoradiotherapy Regimens and Survival Among Patients With Nasopharyngeal Carcinoma: A Systematic Review and Meta-analysis

IMPORTANCE

The role of induction chemotherapy (IC) or adjuvant chemotherapy (AC) in the treatment of locoregionally advanced nasopharyngeal carcinoma (NPC) remains controversial.

OBJECTIVES

To update meta-analyses on the association of survival outcomes with IC and AC regimens in patients with locoregionally advanced NPC and assess whether the current evidence is conclusive by a trial sequential analysis (TSA) approach.

DATA SOURCES

PubMed, Embase, and Web of Science were searched for articles published from inception until June 1, 2019.

STUDY SELECTION

Randomized clinical trials that assessed the efficacy of radiotherapy with or without chemotherapy among previously untreated patients and patients with nondistant metastatic NPC.

DATA EXTRACTION AND SYNTHESIS

Data were extracted by 2 investigators from each trial independently and synthesized by the 2 investigators. All trial results were combined and analyzed by a fixed- or random-effects model.

MAIN OUTCOMES AND MEASURES

Overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS), and locoregional recurrence-free survival (LRFS).

RESULTS

A total of 8036 patients (median age, 46.5 years; 5872 [73.1%] male) from 28 randomized clinical trials were included in the analysis. Pooled analyses revealed that concurrent chemoradiotherapy (CCRT) was significantly associated with improved OS, PFS, DMFS, and LRFS compared with radiotherapy across all subgroups. The TSA confirmed the treatment outcomes of CCRT compared with radiotherapy. The additional IC regimen was associated with an improvement in OS (hazard ratio [HR], 0.84; 95% CI, 0.74-0.95), PFS (HR, 0.73; 95% CI, 0.64-0.84), DMFS (HR, 0.67; 95% CI, 0.59-0.78), and LRFS (HR, 0.74; 95% CI, 0.64-0.85). These findings were consistent in subgroup analyses of multicenter trials with sample sizes greater than 250, years of survival rate of 5 or greater, median follow-up longer than 5 years, or low risk of bias. However, the additional AC regimen was not associated with a survival benefit in OS (HR, 0.98; 95% CI, 0.78-1.23), PFS (HR, 0.86; 95% CI, 0.70-1.07), DMFS (HR, 0.84; 95% CI, 0.64-1.10), or LRFS (HR, 0.80, 95% CI, 0.59-1.09). The TSA provided sound evidence on the additional benefit of IC but not AC.

CONCLUSIONS AND RELEVANCE

These data suggest a significant association of survival outcomes with CCRT in patients with locoregionally advanced NPC. The addition of IC instead of AC could achieve survival benefits. The potential therapeutic gain of AC should be explored in the future.

[Analysis on geographic distribution of high blood pressure prevalence in children and adolescents aged 7-18 years in China, 2014]

Objective: To understand and evaluate the characteristics of geographic distribution of high blood pressure prevalence in children and adolescents aged 7-18 years in China in 2014, and provide evidence for the prevention of hypertension in children and adolescents. Methods: The data of 2014 Chinese National Surveys on Students Constitution and Health conducting 31 provinces (except Hong Kong, Macao and Taiwan) were collected. A total of 216 299 children and adolescents who had complete blood pressure records were selected as study subjects. The low, middle and high prevalence areas were identified according to their high blood pressure detection rates in the children and adolescents,<4%, 4%-7% and >7%, to analyze the geographic distribution of high blood pressure prevalence in the children and adolescents. The environmental data in the capitals of 31 provinces in 2014 were collected to analyze the correlation between environmental factors and blood pressure Z score in the children and adolescents. Results: The average detection rates of high blood pressure was 6.4% in 31 provinces (1.5%-14.2%). The high prevalence areas were mainly distributed in the eastern China, especially the Circum-Bohai sea area, low prevalence areas were mainly distributed in the central and western areas of China and some provinces in the east. Correlation analysis results showed that the annual average temperature, annual average air humidity and local altitude were negatively correlated with blood pressure Z score, including diastolic and systolic blood pressure, in both boys and girls. The annual average sunshine time, PM(2.5) and PM(10) concentrations, content of SO(2) were positively correlated with blood pressure Z score in both boys and girls. Conclusions: There was a significant difference in high blood pressure of children and adolescents among 31 provinces. More attention should be paid to the children and adolescents living high prevalence area. And it is necessary to understand environmental factors which can affect the blood pressure of children and adolescents.

[Surveillance data on notifiable infectious diseases among students aged 6-22 years in China, 2011-2016]

Objective: To analyze the epidemiological characteristics of notifiable infectious diseases among Chinese students from 2011 to 2016 and to provide reference for the effective prevention and control programs on infectious disease among students. Methods: Both morbidity and mortality of notifiable infectious diseases among Chinese students aged 6-22 years from 2011 to 2016 were analyzed, with main characteristics of the disease described. Results: During 2011 to 2016, morbidities of Categories A, B and C infectious diseases among the Chinese students aged 6-22 years showed a decreasing trend, from 248.24/100 000 in 2012 to 158.57/100 000 in 2016. Mortality rates of Category A, B and C infectious diseases had also decreased from 0.12/100 000 in 2011 to 0.07/100 000 in 2016. The average morbidity of the top four diseases from Category A and B infectious diseases appeared as: tuberculosis (16.24/100 000), scarlet fever (9.39/100 000), hepatitis B (7.69/100 000) and bacillary and amebic dysentery (7.15/100 000). The average rates of mortality on the top four diseases appeared as: rabies (0.044 8/100 000), HIV/AIDS (0.027 7/100 000), tuberculosis (0.008 0/100 000) and Japanese encephalitis (0.005 9/100 000). The average rates of morbidity on the top four diseases appeared as: mumps (75.81/100 000), hand-foot-mouth disease (28.55/100 000), other infectious diarrhea (22.41/100 000) and influenza (15.67/100 000) in the Category C. Reported death cases were from hand-foot-mouth disease (11 cases), influenza (9 cases), mumps (1 case) and rubella (1 case). The prevalence rates varied among different student populations, with higher HIV/AIDS, hepatitis B and tuberculosis rates among college and senior high school students, while higher mumps, influenza and hand-foot-mouth disease rates among primary school and junior high school students. Conclusions: Both morbidity and mortality of notifiable infectious diseases among Chinese students aged 6-22 years had decreased significantly in 2011-2016. However, the major infectious diseases had become new challenges among students. HIV/AIDS had become a key infectious disease among college students and the relatively high prevalence of tuberculosis was seen in college and high school students.

[The change in mortality and major causes of death among Chinese adolescents from 1990 to 2016]

Objective: To analyze the change in mortality and major causes of death among Chinese adolescents aged 10-19 years from 1990 to 2016. Methods: Data of death for Chinese adolescents aged 10-19 years were extracted from the Global Burden of Disease Study 2016 (GBD 2016). The data was used to describe the change in mortality of Chinese adolescents from 1990 to 2016.Top 15 causes of death were compared between 1990 and 2016. Results: From 1990 to 2016, the all-cause mortality of Chinese adolescents aged 10-19 years old dropped from 102.5/100 000 to 41.2/100 000, reaching about a half of the global average (78.6/100 000) but still almost twice as high as the average of high-income countries (24.3/100 000) by 2016; the reduction in mortality was higher among females than that among males (decreased 68.7% vs. 54.7%), and among adolescents aged 10-14 years than that among those aged 15-19 years (decreased 62.1% vs. 57.1%). During the 26-year period, the cause-specific mortality of all top 15 causes saw sharp decreases. Among them, communicable, maternal, and nutritional diseases saw the most significant decrease (78.1%), and its proportion in all adolescent deaths fell from 11.1% to 6.1%. Meanwhile, non-communicable diseases and injuries saw relatively small decreases (58.2% and 57.3% respectively), and their proportions rose from 33.4% and 55.6% to 34.8% and 59.1%, respectively. The top 5 causes of death changed from drowning (17.39/100 000 in mortality, 17.0% in proportion), road injuries (14.77/100 000, 14.4%), self-harm (11.44/100 000, 11.2%), leukemia (5.48/100 000, 5.4%) and interpersonal violence (3.12/100 000, 3.0%) in1990 into road injuries (9.27/100 000, 22.5%), drowning (6.83/100 000, 16.6%), leukemia(2.73/100 000, 6.6%), self-harm (2.53/100 000, 6.2%) and congenital birth defects (1.76/100 000, 4.3%) in 2016, and tuberculosis, poisonings and rheumatic heart disease had dropped out of the top 15 in 2016. Conclusion: The mortality of Chinese adolescents aged 10-19 years has decreased significantly, but still higher than developed countries. Since 1990, injuries,especially for road injuries and drowning, have always been the leading causes of death among Chinese adolescents aged 10-19 years, followed by non-communicable diseases.

[Clinical features and gene analysis of TBC1D24 gene mutation related early-onset focal myoclonic epilepsy]

Objective: To investigate the clinical features and genetic characteristics of patients with TBC1D24 gene mutation related early-onset focal myoclonic epilepsy. Methods: Clinical data of 3 patients with TBC1D24 gene mutation related early-onset focal myoclonic epilepsy of Xuanwu Hospital from November 2016 to June 2017 was collected and analyzed.Candidate gene mutations were screened by second generation sequencing. Results: Among the 3 patients, 1 was male and 2 were females.Seizure onset age was 4 months, 3 years and 5 years after birth respectively. Two patients had family history of epilepsy.They all had prolonged episodes of focal myoclonus. Two patients had mental retardation.Scalp electroencephalograms (EEG) was recorded in all 3 cases and myoclonic seizures were captured.The ictal EEGs were normal in all cases. In one patient, the ictal EEG of generalized seizure showed alpha rhythm originating from left fronto-central region. Brain magnetic resonance imaging (MRI) was normal in 2 patients. Abnormal signal was found bilaterally in cerebellum in 1 patient. The gene screening showed that two patients carried compound heterozygous mutation of TBC1D24 gene and one carried homozygous mutation, all of which were de novo mutations.All the patients were treated with multiple antiepileptic drugs (AEDs) and seizures were uncontrolled in 2 patients. One patient was followed up for 10 months without recurrence. Conclusions: TBC1D24 gene related early-onset focal myoclonic epilepsy is clinically characterized by early onset, prolonged focal myoclonus which relieved with sleep, mental retardation and poor response to AEDs.The interictal and ictal EEG usually show normal. Genetic analysis can assist in diagnosis and genetic counseling.

[The association between the malnutrition and blood pressure in Chinese Han students aged 7-18 years in 2014]

Objective: This study aimed to explore the association between malnutrition and the level of blood pressure (BP) as well as elevated BP (EBP) in Han students aged 7 to 18 years in China. Methods: 170 037 subjects with normal nutritional status and malnutrition were enrolled in this study from 2014 Chinese National Surveys on Students' Constitution and Health with a multi-stage stratified cluster random sampling framework covering 31 provinces, autonomous regions and municipalities after the exclusion of 44 317 overweight and obese students. According to the standard of "Screening Standard for Malnutrition of School-age Children and Adolescents" (WS/T456-2014), the nutritional status of children were classified into two categories, normal nutritional status and malnutrition containing stunting, mild wasting and moderate severe wasting. The level of BP and prevalence of EBP were compared between students with normal nutritional status and malnutrition. The multivariate logistic regression model was used to analyze the association between malnutrition and EBP. Results: The levels of systolic BP (SBP) and diastolic BP (DBP) in Chinese Han students aged 7-18 years who were non-overweight and non-obesity status were (103.4±12.3) and (64.7±9.5) mmHg (1 mmHg=0.133 kPa), respectively. The prevalence of EBP, systolic EBP and diastolic EBP in Chinese Han malnourished students (N=21 012) were 3.1% (n=649), 1.5% (n=324) and 2.1% (n=445), respectively, which was significantly lower than those (N=148 320) with normal nutritional status (4.5% (n=6 707), 2.6% (n=3 872) and 2.7% (n=3 959)), and the corresponding differences were statistically significant (P<0.05). The OR (95%CI) between malnutrition and EBP was 0.68 (0.62-0.73), which were 0.65 (0.58-0.72) and 0.68 (0.60-0.77) for boys and girls. The OR (95%CI) between EBP and stunting as well as mild wasting and moderate severe wasting were 0.69 (0.62-0.77), 0.63 (0.55-0.72) and 0.79 (0.60-1.05), respectively. Conclusion: The level of BP and prevalence of EBP in Chinese Han students with malnutrition were lower than those with normal nutritional status. The negative correlation existed between malnutrition and EBP in Chinese Han students aged 7 to 18 years.

[The epidemiological characteristics and related factors of dyslipidemia among children and adolescents aged 6-17 years from 7 provinces in China, 2012]

Objective: To investigate the prevalence and related factors of dyslipidemia among children and adolescents aged 6-17 years in 7 provinces in China. Methods: Using the method of stratified cluster random sampling, 93 primary and secondary schools were selected from Guangdong, Hunan, Liaoning provinces, Shanghai, Chongqing, Tianjin municipalities and Ningxia Hui Autonomous Region in China, 2012. A total of 16 434 students aged 6-17 years old with completed physical and lipid profiles parameters were selected into this study from above 93 primary and secondary schools. Dyslipidemia was determined by the definition of Expert Advice on Prevention and Treatment of Dyslipidemia in Children and Adolescents in 2009. Logistic regression model was used to explore the factors related to dyslipidemia. Results: The prevalence of elevated total cholesterol, elevated triglyceride, elevated low-density lipoprotein cholesterol, low high-density lipoprotein cholesterol, and dyslipidemia was 5.4% (887 cases), 15.7% (2 578 cases), 3.0% (492 cases), 13.5% (2 221 cases) and 28.5% (4 679 cases) among children and adolescents aged 6-17 years, respectively. Sugary drinks intake ≥once per week (OR=1.14; 95%CI: 1.05-1.24), sedentary time >10 hours per day (OR=1.14, 95%CI: 1.01-1.28), overweight (OR=1.50, 95%CI: 1.33-1.70), and obesity (OR=2.62, 95%CI: 2.31-2.96) were significantly associated with the prevalence of dyslipidemia. Conclusion: The prevalence of dyslipidemia was high among children and adolescents aged 6-17 in 7 provinces in China, 2012. Sugary drinks intake ≥once per week, sedentary time >10 hours per day, overweight and obesity might be the risk factors of dyslipidemia among children and adolescents.

[Analysis on prevalence of physical fitness and related influencing factors among Chinese Han students aged 13-18 years in 2014]

Objective: To analyze the prevalence of physical fitness among Chinese Han students aged 13-18 years in 2014, and explore related influencing factors. Methods: This study recruited 106 881 Han students aged 13-18 years who had taken physical fitness test from Chinese National Survey on Students' Constitution and Health in 2014. After the exclusion of 1 047 students without complete records of physical fitness test, 105 834 students were included in the final analysis. According to the National Student Physical Health Standard modified in 2014, seven indicators including body mass index, vital capacity, 50-m run, sit-and-reach, standing broad jump, pull-ups/curl-ups and endurance run were tested to calculate the total score of students' physical fitness. Students with score ≥60 were regarded as qualified students. Multivariate non-conditional logistic regression model was used to analyze influencing factors of physical fitness. Results: Among Chinese Han students aged 13-18 years, the total score was 70.1±10.7 and the qualified rate was 83.9% (n=88 813). Boys (83.5% (44 197/52 910)) had a lower qualified rate of physical fitness than girls (84.3% (44 616/52 924)) (P<0.001), and 13-15 age group (86.5% (46 255/53 465)) was higher than the 16-18 age group (81.3% (42 558/52 369)) (P<0.001). Except for 16-18-year-old boys from central region, normal body mass index, eastern region, good socioeconomic status, enough PE class, exercise time ≥1 h/d, homework time ≥2 h/d, TV time <1 h/d were all related to high qualified rates of physical fitness (P<0.05). Conclusion: Chinese Han students aged 13-18 years were in good physical condition. The qualified rates of physical fitness were significantly different by gender and age groups. Nutritional status, region, socioeconomic status, PE class, exercise time per day, homework time per day, and TV time per day were related factors of physical fitness.

[Association between speed and endurance performance with sleep duration in children and adolescents]

OBJECTIVE

To analyze the association between sleep duration and athletic performance, and provide scientific basis to improve the 50 m and endurance performance in children and adolescents.

METHODS

All the 119 462 subjects aged 9-15 years in both genders were sampled from 2014 National Physical Fitness and Health Surveillance by using stratified random cluster sampling method, to measure the height, weight, 50 meters and endurance performance and investigate sleep duration with questionnaire. Their body mass indexes (BMI) were calculated and the students' 50 m, endurance run scores and sleep durations were assessed. Binary Logistic regression was used to analyze the difference between the different sleep groups, and multifactor Logistic regression was used to analyze the relationship between the sleep condition and athletic performance.

RESULTS

The prevalence of insufficient sleep was 94.67% in the total subjects, the prevalence was higher among the girls (95.26%)than the boys (94.09%, χ²=80.99, P<0.001), and higher among the urban (95.41%) than the rural students(93.93%, χ²=128.48, P<0.001).The children with sufficient sleep had better performance in 50 m and endurance run scores( χ²_{50 m}=10.10, P_{50 m}＜0.01; χ²_{endurance run}=21.76, P<0.001). Logistic regression analysis after controlling the gender, area, grade and BMI showed that children with adequate sleep showed better results(OR_{50 m}=1.14, 95%CI_{50 m}=1.05-1.23, P_{50 m}<0.01; OR_{endurance run}=1.21, 95%CI_{endurance run}=1.11-1.31, P_{endurance run}<0.001). As for gender, the excellent rates of 50 m and endurance run scores in the boys with adequate sleep were higher (P<0.001), but there were no significant difference in 50 m and endurance run excellent rates in the girls of different sleep conditions. The excellent rates of 50 m and endurance run in the urban children and the endurance rate in the rural children and adolescents with adequate sleep were higher than those with insufficient sleep (P<0.01) while there were no significant difference in the 50 m excellent rates between the different sleep groups in rural areas. The 50 m and endurance run excellent rates of the children and adolescents with adequate sleep in each grade were higher than those of the children in the same grade with insufficient sleep (P_{primary students' endurance performance}<0.001, and the rest P<0.05). Children and adolescents with normal BMI and overweight who slept well had better performance in 50 m (P<0.05). The endurance run excellent rate of children and adolescents with adequate sleep in each BMI group was higher than that in children and adolescents with insufficient sleep in the same BMI group (P_malnutrition<0.01, P_normal<0.01, P_overweight<0.05, P_obesity<0.05). The children and adolescents were divided into different groups according to the sleep duration,the one who slept less than 7 hours had lower 50 m excellent rate than the other groups with longer sleeping duration (P<0.01) and the rate in the ones who slept more than 9 hours was the highest (P<0.001).The endurance excellent rate in the children and adolescents who slept more than 9 hours was significantly higher than that in the other groups (P<0.001).There was no significant dose-response relationship in excellent rates and sleep durations.

CONCLUSION

The prevalence of insufficient sleep has increased, and the sleep condition in children and adolescents is severe. Children and adolescents with sufficient sleep have better athletic performance, so we should strengthen the prevention and control of the lack of sleep in children and adolescents.

[Association between the blood pressure status and nutritional status among Chinese students aged 7-18 years in 2014: based on the national blood pressure reference for Chinese children and adolescents]

OBJECTIVE

To analyze the epidemic situation of blood pressure (BP) status and its association with nutritional status among Chinese children and adolescents aged 7-18 years old in 2014, and to provide important scientific basis for the control of students' hypertension.

METHODS

All the subjects aged 7 to 18 years in both genders were sampled from 2014 Chinese national surveys on students' constitution and health. BP status was evaluated according to Chinese national gender-, age- and height-specific references, including hypertension (HTN), elevated hypertension (elevated HTN), isolated systolic HTN (SHTN), isolated diastolic HTN (DHTN) and mix HTN. Their nutritional status was evaluated using the international obesity task force (IOTF) definition, including thinness (severe thinness and moderate thinness), normal, overweight and obesity (severe obesity and moderate obesity). The Logistics method was used to analyze the association between BP status and nutritional status. The population attributable risk (PAR%) of overweight and obesity for BP status was calculated.

RESULTS

The prevalence of HTN and elevated HTN among the Chinese children and adolescents aged 7-18 years in 2014 was 14.9% and 9.2%, respectively. And the prevalence of isolated SHTN, isolated DHTN and mix HTN was 3.1%, 8.8% and 3.0%, respectively. The prevalence estimates for HTN differed the greatest for the boys, those in rural, those with high age, those in the East, and those with high BMI. The highest prevalence of HTN was detected in those with severe obesity with 44.2% and 38.8% in the boys and girls respectively, which was 2.8-fold and 3.7-fold than those with normal groups. The negative association was detected between HTN and thinness, but the positive association with overweight and obesity. The PAR% of HTN due to overweight and obesity was 16.2%, and the expected prevalence of HTN was 12.5% if controlling for overweight and obesity. Higher PAR% of isolated SHTN and mix HTN due to overweight and obesity was detected in the Chinese children and adolescents with proportions of 28.7% and 35.1%.

CONCLUSION

The prevalence of HTN among the Chinese children and adolescents aged 7-18 years was still high, whose components mainly focused on isolated DHTN. Overweight and obesity can increase the risk of HTN in children and adolescents significantly, especially for isolated SHTN and mix HTN. Controlling for overweight and obesity can decrease the risk of HTN among Chinese national children and adolescents largely, which can play an important role in preventing the occurrence of chronic disease in adults.

[Association between cesarean birth and the risk of obesity in 6-17 year-olds]

Objective: To explore the association between cesarean section and obesity in child and adolescent. Methods: In this study, a total number of 42 758 primary and middle school students aged between 6 and 17 were selected, using the stratified cluster sampling method in 93 primary and middle schools in Hunan, Ningxia, Tianjin, Chongqing, Liaoning, Shanghai and Guangdong provinces and autonomous regions. Log-Binomial regression model was used to analyze the association between cesarean section and obesity in childhood or adolescent. Results: Mean age of the subjects was (10.5±3.2) years. The overall rate of cesarean section among subjects attending primary or secondary schools was 42.3%, with 55.9% in boys and, 40.6% in girls respectively and with difference statistically significant (P<0.001). The rate on obesity among those that received cesarean section (17.6%) was significantly higher than those who experienced vaginal delivery (10.2%) (P<0.001). Results from the log-binomial regression model showed that cesarean section significantly increased the risk of obesity in child and adolescent (OR=1.72, 95%CI: 1.63-1.82; P<0.001). After adjusting for factors as sex, residential areas (urban or rural), feeding patterns, frequencies of milk-feeding, eating high-energy foods, eating fried foods and the levels of parental education, family income, parental obesity, physical activity levels, gestational age and birth weight etc., the differences were still statistically significant (OR=1.48, 95%CI: 1.39-1.57; P<0.001). Conclusion: The rate of cesarean section among pregnant women in China appeared high which may significantly increase the risk of obesity in child or adolescent.

[Trends in overweight and obesity among Chinese children of 7-18 years old during 1985-2014]

Objective: To investigate the trends in overweight and obesity in Chinese students during 1985-2014. Methods: Data were collected from the Chinese National Survey on Students Constitution and Health in 1985, 1995, 2000, 2005, 2010, and 2014, with the sample size of 409 946, 204 977, 216 786, 234 421, 215 319, and 214 354, respectively. The prevalence of overweight and obesity as well as the increase rates were calculated based on the body mass index (BMI) percentile criteria of Working Group on Obesity in China (WGOC). Results: The prevalence of overweight and obesity in 2014 was 19.4% (41 608/214 354) among 7-18 y Chinese children. The prevalence of overweight and obesity was 24.2% (25 975/107 216) among boys, and 14.6% (15 633/107 138) among girls, with the prevalence among boys exceeding girls (P<0.001). The prevalence of overweight and obesity was 22.3% (23 911/107 239) among urban students, and 16.5% (17 697/107 115) among rural students, with the prevalence among urban students exceeding rural students (P<0.001). The prevalence in 2014 differed among provinces, ranging from 2.3% (Hainan Province 166/7 200) to 16.3% (Tianjin 168/7 186). During 1985-2014, the prevalence of overweight and obesity among 7-18 y Chinese children increased continuously, with the annual increase rate of overweight ranging 0.27%-0.63%, and the annual increase rate of obesity ranging 0.10%-0.58%. The annual increase rates in 2010-2014 of obesity among the urban boys, urban girls, rural boys and rural girls were 0.62%, 0.42%, 0.79%, and 0.49%,respectively, peaking the annual increase rates during 1985-2014. Conclusion: The prevalence of overweight and obesity among 7-18 y Chinese children increased continuously during 1985-2014, with the annual increase rate of obesity in 2010-2014 peaking the increase rates during 1985-2014. There were gender and regional differences in the prevalence of overweight and obesity among 7-18 y Chinese children in 2014.

[The epidemic status and secular trends of myopia prevalence for Chinese children and adolescents aged 7-18 years from 2005 to 2014]

Objective: To investigate the characteristics of geographic distribution and change trend of myopia prevalence for children and adolescents aged 7-18 years old from 2005 to 2014, which provides the basis for the prevention of myopia. Methods: Research material was selected from the data of 2005, 2010, and 2014 Chinese National Survey on Students Constitution and Health, including 31 provinces (with the exception of Hong Kong, Macao, and Taiwan). The complete detection data of binoculus in children and adolescents aged 7-18 years old were selected as our research objects. The research objects of three studies were 233 505, 216 474, and 215 160, respectively. We analyzed the characteristics of geographic distribution and change trend of myopia prevalence for children and adolescents aged 7-18 years old in 31 provinces from 2005 to 2014. Results: The overall myopia detection rates in Chinese children and adolescents aged 7 to 18 years old in 31 provinces were 47.4% (111 707/235 505), 55.6% (120 456/216 474), and 57.2% (122 965/215 160) in 2005, 2010 and 2014, respectively. The growth range in this two phases were 8.0 percentage points, and 1.6 percentage points, respectively, and the difference was statistically significant (P<0.05). The detection rate of Myopia was growing quickly from 2005 to 2010 and only three provinces were in the situation of decline state including Tianjin, Hainan, and Ningxia. 90.3 percent (28/31) of provinces were in the situation of growth state and the growth range was 1.3%-22.3%. The growth of myopia was in the situation of slowdown from 2010 to 2014, and 38.7 percent (12/31) of the provinces were in negative growth districts including Hebei, Shanxi, Inner Mongolia, Zhejiang, Fujian, Shandong, Hubei, Guangxi, Guizhou, Tibet, Qianghai, and Xinjiang. The growth range in other provinces was 0.4%-24.7%. Conclusion: The myopia detection rate was at a higher level and growing constantly in China. There was large difference for myopia of children and adolescents among the 31 provinces. However, the overall growth rate of myopia in children and adolescents was in the situation of a relatively low level form 2010 to 2014.

[Study on the disease burden of Chinese adolescent in 2015]

Objective: To discuss the main causes and risk factors of disability and death among current Chinese adolescents. Methods: Subnational data of China from Global Burden of Disease Study 2015 (GBD 2015) was used to rank the causes and risk factors leading to death and disability adjusted life years (DALY) in Chinese adolescents aged between 10 and 19 years old, and thereby to analyze the main cauese and risk factors of death and DALY among Chinese adolescents in different genders. Results: In 2015, among Chinese adolescents aged 10-19 years old, the total DALY was 13 million 490 thousand years, and the total number of deaths was 63 258 cases. The top 3 causes of DALY were skin and subcutaneous diseases, iron-deficiency anemia and road injuries, resulting in DALY (constituent ratio) of 1 411 (10.5%), 1 094 (8.1%) and 1 029 (7.6%) thousand years respectively. The top 3 causes of death were road injuries, drowning and leukemia, causing 13 881 (21.9%), 9 895 (15.6%) and 4 620 (7.3%) deaths (constituent ratio) respectively. The top 3 risk factors of DALY were iron deficiency, alcohol use and drug use, causing 1 094 (8.1%), 487 (3.6%) and 220 thousand years (1.6%) DALY (constituent ratio) respectively. The top 3 risk factors of death were alcohol use, occupational injuries and drug use, causing 5 957 (9.4%), 1 523 (2.4%) and 810 (1.3%) deaths respectively. Conclusion: Unintentional injury was the top cause of DALY and death in Chinese adolescents, followed by skin and subcutaneous diseases and iron-deficiency anemia. Iron deficiency and alcohol use were the top two risk factors of DALY and death.

[Analysis on prevalence of physical activity time <1 hour and related factors in students aged 9-22 years in China, 2014]

Objective: To explore the prevalence of physical activity time <1 hour and related factors in students aged 9-22 years in China. Methods: A total of 220 159 students (110 039 boys and 110 120 girls) aged 9-22 years who completed the questionnaire of physical activity and lifestyle behaviors were selected from " 2014 National Physical Fitness and Health Surveillance" for the current study. All the participants were divided into 2 groups, i.e. physical activity time <1 hour and physical activity time ≥1 hour according the suggestion of Central Government, stratified by age and gender. χ(2) tests were used to compare the difference in the prevalence of physical activity time <1 hour between boys and girls in every age groups. Univariate and multivariate log-binomial regression models were used to explore the factors that influenced the prevalence of physical activity time <1 hour. Results: The boy's prevalence of physical activity time <1 hour was 73.3%, with the lowest (57.0%) in 9-years-old group, and highest (82.5%) in 18 years old group. The girl's prevalence of physical activity time <1 hour was 79.1%, with the lowest (60.1%) in 9-years-old group, and highest (89.8%) in 21 years old group. Overall, The prevalence of physical activity time <1 hour was significantly higher in girls than in boys (P<0.001), and the prevalence were significantly higher in girls than in boys in all the age groups (P<0.001), and it was observed that the prevalence of physical activity <1 hour increased with age in both boys and girls (P<0.001). Multivariate log-binomial regression model found that being girl (PR=1.05, 95%CI: 1.05-1.06), parents' disliking children to participate physical activity (PR=1.08, 95% CI: 1.07-1.09), heavy homework (PR=1.13, 95% CI: 1.12-1.14), long homework time (PR =1.08, 95%CI: 1.07-1.08), long time spending on electronic screen watching (PR=1.01, 95%CI: 1.00-1.01) and disliking physical class (PR=1.11, 95%CI: 1.10-1.12) could be the risk factors for physical activity time <1 hour, however, living in rural area (PR=0.99, 95% CI: 0.98-0.99) and no supporting from parents for children to participate physical activity (PR=0.99, 95%CI: 1.98-1.00) could be the protective factors, but no consistent association with the time of TV watching was observed (P=0.226). Conclusions: The prevalence of physical activity time <1 hour was high in students aged 9-22 years in China. Female, parents; disliking children to participate physical activity, heavy homework, long homework time, long electronic screen watching time and disliking physical class might be the risk factors.

[Prevalence of myopia and increase trend in children and adolescents aged 7-18 years in Han ethnic group in China, 2005-2014]

Objective: To understand and evaluate the prevalence of myopia and its trend in children and adolescents aged 7-18 years in Han ethnic group in China from 2005 to 2014, and provide evidence for the prevention of myopia. Methods: The data of 2005, 2010 and 2014 Chinese National Students Constitution and Health Surveys were collected. The children and adolescents with complete detection data of binoculus were selected as study subjects. The sample size of three studies were 233 108, 215 319 and 212 743, respectively. The method of curve fitting was used to simulate the myopia detection increase model and analyze the gender and area specific myopia detection increase trends and characteristics from 2005 to 2014. Results: The overall myopia detection rate increased gradually in the children and adolescents aged 7 to 18, which was 47.5% in 2005, 55.5% in 2010 and 57.1% in 2014, respectively. The increase slowed in 2014. A"parabola" shape of myopia detection increase rate was observed. Myopia detection rate increased with age before puberty and decreased with age after puberty gradually. A"cross phenomenon" of myopia detection increase was observed in boys and girls between urban and rural areas. The increase of myopia detection was mainly in urban students before puberty and in rural students after puberty. The age of myopia prevalence peak has become earlier constantly in children and adolescents aged 7-18 years from 2005 to 2014, which was 13 years old in 2005, 12 years old in 2010 and 11 years old in 2014. The increase rate was about 7%. During 2005-2014, the increase rate of myopia detection gradually increased in younger students and tended to zero in older students. Conclusion: The detection rate of myopia was still high in children and adolescents in China. The age of myopia prevalence peak has become earlier gradually.

To predict the radiosensitivity of nasopharyngeal carcinoma using intravoxel incoherent motion MRI at 3.0 T

PURPOSE

To investigate intravoxel incoherent motion (IVIM) MRI for evaluating the sensitivity of radiotherapy on nasopharyngeal carcinoma (NPC).

RESULTS

The reproducibility between intra-observer and inter-observer was relatively good. D (0.72×10^-3 mm²/s±0.14 vs. 0.54×10^-3 mm²/s±0.23; P < 0.001) and D* (157.92×10^-3 mm²/s±15.21 vs. 120.36×10^-3 mm²/s±10.22; P < 0.0001) were significantly higher in effective group than poor-effective group, whereas the difference of f (18.79%±2.51 vs. 16.47%±1.51) and ADC (1.21×10^-3 mm²/s±0.11 vs. 1.33×10^-3 mm²/s±0.23) could not reach statistical significant between the 2 groups (P > 0.05).

CONCLUSIONS

IVIM may be potentially useful in assessing the radiosensitivity of NPC. The higher D value combining with higher D* value might indicate the more radiosensitive of NPC, and increased D* might reflect increased blood vessel generation and parenchymal perfusion in NPC.

MATERIALS AND METHODS

Sixty consecutive patients (20 female, range, 27-83 years, mean age, 52 years) newly diagnosed NPC in the stage of T3 or T4 were enrolled. Forty-two of them were divided into effective group clinically after a standard radiotherapy according to the RECIST criteria. IVIM with 13 b-values (range, 0-800 s/mm²) and general MRI were performed at 3.0T MR scanner before and after radiotherapy. The parameters of IVIM including perfusion fraction (f), perfusion-related diffusion (D*), pure molecular diffusion (D) and apparent diffusion coefficient (ADC) were calculated. Two radiologists major in MRI diagnose analyzed all images independently and placed regions of interest (ROIs). Intra-class correlation coefficient (ICC) was used to evaluate intra-observer and inter-observer agreement. And Mann-Whitney test was used to assess the differences between the two groups.

[Analysis of association between appendicular skeletal muscle mass index and main anthropometric parameters among overweight and obese adults in China]

Objective: To investigate the associations between the appendicular skeletal muscle mass index and main anthropometric parameters, and to provide clues for preventing the reduction of skeletal muscle mass among overweight and obese adults in China. Methods: 1 488 volunteered participants who resided in Beijing longer than one year, between 22 and 55 years old, with self-report BMI ≥24 kg/m(2) were recruited from April to May 2014. 171 participants whose BMI ≤24 kg/m(2) or with organic diseases at the first physical examination were excluded, finally 1 317 overweight/obese participants (male and female were 507, and 810, respectively) were enrolled into the present study. After measuring the anthropometric parameters and body composition by the DXA, Pearson correlation analysis and multiple linear regression models were used to analyze the associations between the appendicular skeletal muscle mass index and main anthropometric parameters. Results: The average age of males and females was (35.6±8.4) and (38.2±9.4) years old, respectively. The females' mean levels of body fat percentage, BMI, waist circumference, hip circumference, and bone mineral density were (41.59±4.14)%, (29.00±3.75) kg/m(2), (92.56±9.00) cm, (101.74±6.75) cm, and (1.20±0.10) g/cm(2), respectively; and the males' mean levels were (34.22±4.61)%, (30.07±4.12) kg/m(2), (99.63±9.49) cm, (102.93±7.28) cm, and (1.28±0.11) g/cm(2), respectively. The mean level of appendicular skeletal muscle mass and skeletal muscle mass index in males were (26.98±3.88), and (8.96±1.02) kg, respectively, which were significantly higher than it in females ((18.57±2.61), and (7.26±0.83) kg, respectively) (P<0.001). For male, the correlation coefficients of skeletal muscle mass index with BMI, waist circumference, hip circumference, body fat percentage and bone mineral density were 0.814, 0.601, 0.637, 0.558, and 0.434, respectively; for female, the correlation coefficients of skeletal muscle mass index with BMI, waist circumference, hip circumference, body fat rate and bone mineral density were 0.761, 0.534, 0.585, 0.610, and 0.304, respectively. The correlations were statistically significant (P<0.001). Multiple linear regression analysis showed that the skeletal muscle mass index of male decreased with the increase of age (β=-0.01, 95%CI:-0.01-0.00) and body fat percentage (β=-0.13, 95%CI:-0.15--0.12) (P<0.05), while increased with the increase of BMI (β=0.31, 95%CI: 0.29-0.32) and bone mineral density (β=0.54, 95%CI: 0.10-1.01) (P<0.05). The skeletal muscle mass index of female decreased with the increase of age (β=-0.01, 95%CI:-0.01-0.00) and body fat percentage (β=-0.12, 95%CI:-0.14--0.12) (P<0.05), while increased with the increase of BMI (β=0.26, 95%CI: 0.25-0.28) and hip circumference (β=0.01, 95%CI: 0.00-0.02) (P<0.05). Conclusion: The skeletal muscle mass index of male was higher than it of female. For male, the skeletal muscle mass index might be associated with age, BMI, body fat percentage and bone mineral density. While for female, the skeletal muscle mass index might be associated with age, BMI, body fat percentage and hip circumference.

[A cross-section study on physical endurance level in primary and middle school students in China, 2014]

Objective: To understand the physical endurance level of primary and middle school students in China in 2014, and identify the factors influencing students'physical endurance. Methods: Data were collected from"National School Student Physical Fitness and Health Surveillance in 2014" , a total of 142 708 primary and middle school students with complete information were included in the analysis. The age, gender and area specific failure rates of endurance running of students were analyzed, the differences were analyzed with χ(2) test, and the factors influencing students' physical endurance were identified with log-binomial regression model. Results: Among the 142 708 students, the failure rate of endurance running was 21.6% (30 867/142 708). The failure rate was 23.7% (16 891/71 388) in boys and 19.6% (13 976/71 320) in girls (χ(2)=347.73, P<0.05). And it was 24.8% in students in urban area (17 713/71 378), higher than that in students in rural area (18.4%, 13 154/71 330) (χ(2)=855.29, P<0.05). The failure rate of endurance running showed an upward trend with age. Insufficient physical education class hour (OR=1.13, 95%CI: 1.11-1.15), not taking breakfast daily (OR=1.22, 95%CI: 1.20-1.25), daily physical exercise time<1 hour (OR=1.44, 95%CI: 1.40-1.48), the screen watching time>2 hours (OR=1.16, 95%CI: 1.14-1.19) and overweight or obesity (OR=1.90, 95%CI: 1.86-1.95) might be the risk factors for the failure of physical endurance. Conclusion: The physical endurance of primary and secondary students in China was not optimistic, and the factors influencing their physical endurance included gender, living area, physical education class time, daily homework time, breakfast, daily exercise time and nutrition status.

[The endemic distribution and related factors of elevated blood pressure among Chinese children and adolescents aged 7-18 years in 2014]

Objective: To investigate the endemic distribution and related factors of elevated blood pressure in Chinese children and adolescents aged 7 to 18 years old. Methods: A total of 214 354 students aged 7 to 18 years old with data integrity of height, weight, and blood pressure were selected from Chinese National Survey on Students Constitution and Health in 2014, including 31 provinces (with the exception of Hong Kong, Macao, and Taiwan) in China. The criterion of elevated blood pressure was defined by the diagnosis and treatment guideline of high blood pressure in US children and adolescent. The differences of elevated blood pressure between boys and girls and different groups of nutritional status were calculated by Chi-square test. Results: The mean values of systolic pressure and diastolic pressure were (104.8 ± 12.8) mmHg (1 mmHg=0.133 kPa), and (65.4 ± 9.7) mmHg, respectively. The rate of elevated blood pressure in Chinese children and adolescents aged 7 to 18 years old was 6.4% (13 558/214 354), as well as 7.0% (7 537/106 982) in boys, and 5.7% (6 131/106 979) in girls (P<0.001). Meanwhile, the rate of elevated blood pressure was 3.2% (321/10 127), 4.9% (7 887/161 419), 9.8% (2 472/25 292), and 17.5% (2 988/17 051) in wasting group, normal group, overweight group and obesity group, respectively, which indicated a rising trend from wasting to obesity among four nutritional status groups(P<0.001). Conclusion: The rate of elevated blood pressure in Chinese boys was higher than girls, especially in overweight and obese students. Therefore, the effective intervention on child and adolescent with overweight or obesity will become the key work on the prevention of high blood pressure in the future.

[Analysis of the epidemiological characteristics of metabolic syndrome among 10-16 adolescents in 7 provinces in China, 2012]

Objective: To investigate the prevalence of metabolic syndrome (MS) among children and adolescents aged 10-16 years old in 7 provinces in China. Methods: Using the method of stratified cluster random sampling, 93 primary and secondary schools were selected from Guangdong, Hunan, Liaoning, Shanghai, Chongqing, Tianjin, and Ningxia provinces in China. A total of 9 296 students aged 10-16 years old with complete physical and biochemical parameters were selected as the subjects of the present study from above 93 primary and secondary schools. MS was determined using the definition of 'guideline of 2010 Chinese children and adolescents MS definition and treatment'. The standardized age-sex composition of the 2010 census was used to standardize the MS detection rate of every province. Chi-square test was used to compare the difference of MS prevalence among participants with different characteristics. Results: The prevalence of MS was 4.1% (384/9 296) among children and adolescents aged 10-16 years old in 7 provinces in China. The prevalence of MS among males was 5.0% (237/4 754), which was significantly higher than females (3.2%) (147/4 542) (P<0.05). Stratified by nutrition conditions, the prevalence of MS was 0, 0.6% (39/6 733), 8.9% (104/1 170), 30.0% (241/803) for thin, normal weight, overweight, and obese population, respectively. The MS prevalence increased with the increase of body mass index (BMI) (P<0.001). Stratified by provinces, the prevalence of MS was the highest in Tianjin (9.2%) and the lowest in Hunan province (0.8%). Conclusion: The prevalence of MS was high among children and adolescents aged 10-16 years old in 7 provinces in China. MS prevalence among males was higher than females; MS prevalence among overweight/obese population was higher than normal weight population. The detection rate of metabolic syndrome was different in different provinces.

Development of polymorphic SSR markers in the razor clam (Sinonovacula constricta) and cross-species amplification

Next-generation sequencing provides large-scale sequencing data with relative ease and at a reasonable cost, making it possible to identify a large amount of SSR markers in a timely and cost-effective manner. On the basis of the transcriptome database of Sinonovacula constricta obtained by Illumina/Solexa pyrosequencing, 60 polymorphic SSR markers were developed and characterized in 30 individuals. The number of alleles per polymorphic locus ranged from 2 to 7 with an average of 3.75 alleles. The observed and expected heterozygosities varied from 0.050 to 1.000 and from 0.050 to 0.836, respectively. Nineteen loci significantly deviated from Hardy-Weinberg equilibrium (P < 0.01) after Bonferroni's correction for multiple tests. In addition, interspecific transferability revealed that 20 polymorphic loci in Solen linearis were first characterized in this study. To the best of our knowledge, this is the highest number of SSRs in S. constricta and the first report of cross-species amplification. These novel polymorphic SSR markers will be particularly useful for conservation genetics, evolutionary studies, genetic trait mapping, and marker assisted selection in the species.

Development of novel polymorphic microsatellite markers for the blood clam Tegillarca granosa by pyrosequencing

Large amounts of expressed sequence tags (ESTs) generated using next-generation sequencing technologies provide a cost-effective and valuable genomic resource for the development of microsatellite markers. In this study, we isolated 115 novel polymorphic microsatellite markers for the blood clam Tegillarca granosa from ESTs in 454 sequencing data. All the loci were characterized in 30 individual clams from a natural population in Xiangshan (Zhejiang Province, China). The number of alleles per locus varied from 2 to 10, with an average of 3.78. The observed and expected heterozygosities ranged from 0 to 1 and from 0.040 to 0.799, respectively. The polymorphic information content (PIC) ranged from 0.038 to 0.825, and 29 highly polymorphic loci (PIC ≥ 0.5) and 42 moderately polymorphic loci (0.25 < PIC < 0.5) were identified. Thirty-eight of the 115 loci deviated significantly from the Hardy-Weinberg equilibrium (P < 0.01) after a Bonferroni correction. A BlastX search revealed that 46 (40%) of the polymorphic loci identified were from transcript regions of known genes. The microsatellite markers developed in the present study will greatly enrich the microsatellite resources of T. granosa, and are available for further population genetic analysis, genetic trait mapping, and molecular-assisted selection.

Microsatellite marker analysis reveals the distinction between the north and south groups of hard clam (Meretrix meretrix) in China

Meretrix meretrix is one of the important commercial bivalves in China. A total of 198 individual clams were collected from 5 locations characteristic of the clam's 5 main natural habitats in China, that is, Shandong, Jiangsu, Fujian, Guangdong, and Guangxi. Ten polymorphic microsatellite markers were selected to examine the genetic diversity and identify genetic differences between the 5 populations. A total of 183 alleles across 10 loci were detected in the individual clams. The observed heterozygosity and expected heterozygosity ranged from 0.197 to 0.7026 and from 0.6264 to 0.9408, respectively. The genetic diversity within samples was high (8.6-11.2 alleles per locus, observed heterozygosity = 0.25-0.875 and expected heterozygosity = 0.6848-0.9259). Most of the genotype distributions significantly deviated from Hardy-Weinberg equilibrium. Genetic structure analysis showed that the 5 populations could be divided into 2 groups, the north and south groups. Neighbor-joining analysis revealed a clear distinction between the north group (Shandong and Jiangsu) and the south group (Fujian, Guangdong, and Guangxi). Locus MM1031 was used to distinguish between groups. Our results can be used for population identification and crossbreeding of M. meretrix.

Bioaccumulation of heavy metals in fish and Ardeid at Pearl River Estuary, China

Sediment, fish (tilapia, Oreochromis mossambicus and snakehead, Channa asiatica), eggs and eggshells of Little Egrets (Egretta garzetta) and Chinese Pond Herons (Ardeola bacchus) were collected from Mai Po Ramsar site of Hong Kong, as well as from wetlands in the Gu Cheng County, Shang Hu County and Dafeng Milu National Nature Reserve of Jiangsu Province, China between 2004 and 2007 (n=3-9). Concentrations of six heavy metals were analyzed, based on inductively coupled plasma optical emission spectrometry (ICP-OES). Significant bioaccumulations of Cd (BAF: 165-1271 percent) were observed in the muscle and viscera of large tilapia and snakehead, suggesting potential health risks to the two bird species, as the fishes are the main preys of waterbirds. Significant (p<0.01) linear relationships were obtained between concentrations of Cd, Cr, Cu, Mn, Pb and Zn in the eggs and eggshells of various Ardeid species, and these regression models were used to extrapolate the heavy metal concentrations in the Ardeid eggs of Mai Po. Extrapolated concentrations are consistent with data in the available literature, and advocate the potential use of these models as a non-invasive sampling method for predicting heavy metal contamination in Ardeid eggs.

Autoimmune thyroid disease: mechanism, genetics and current knowledge

Recent epidemiological studies recognized a steady increase in the incidence of different autoimmune endocrine disorders, including autoimmune thyroid disease (AITD). The etiology of AITD is multifactorial and involves genetic and environmental factors and apparently with a strong preponderance in females. There are mainly two types of AITD, Graves' disease and Hashimoto's disease and both of these show strong association in age groups above 45-50 years. Among environmental factors smoking and alcohol have significant effects, both protective as well as for aggravating the disease, even though the precise nature of these effects are not clearly known. There are elevated levels of circulating antibodies against the thyroid proteins, mainly thyroid oxidase, thyroglobulin and thyroid stimulating hormone receptor, in patients with Graves' disease or Hashimoto's disease. Linkage and association studies in AITD identified several major genes that are relevant for the onset of AITD, including the thyroid-specific genes, thyroglobulin and thyroid-stimulating hormone receptor and also many immune-regulatory genes. In this review we addressed many aspects of AITD including disease mechanisms, involved thyroid antigens, environmental factors and genetic factors.

Biota-sediment accumulation factor (BSAF), bioaccumulation factor (BAF), and contaminant levels in prey fish to indicate the extent of PAHs and OCPs contamination in eggs of waterbirds

Samples of pond sediment, fish, and shrimp were collected from the Ramsar site at Mai Po marshes, Hong Kong (south China), and samples of pond sediment, fish, and shrimp, as well as eggs of water birds (Chinese Pond Herons (Ardeola bacchus) and Little Egrets (Egretta garzetta)), were collected from two smaller wetland sites at Jiangsu Province (mid-China), between 2004 and 2007. Accumulation levels of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in the biota were used to calculate biota-sediment accumulation factor (BSAF) and bioaccumulation factor (BAF). For fish and shrimp, BSAFs of OCPs (3.8-56) were greater than those of PAHs (0.12-6.3). BSAFs and BAFs of 11-79 and 4-34, respectively, were registered for OCPs in eggs of the birds and were greater than those for PAHs (0.11-1.5 and 0.02-1.3, respectively). Assuming that fish were the main prey of the birds, greater bioaccumulation of OCPs was detected for both bird species (BAFs =4.5-34), while accumulation of PAHs was only detected in Little Egret (BAF=1.3). A significant linear relationship (p<0.01) was observed between concentrations of OCPs in bird eggs and in the prey fish. The present study provides a new possibility of using OCP levels detected in prey fish to predict the extent of OCPs contamination in eggs of waterbirds including the endangered species, as a noninvasive method.

A novel quantitative trait locus for Fusarium head blight resistance in chromosome 7A of wheat

A Chinese Spring-Sumai 3 chromosome 7A disomic substitution line (CS-Sumai 3-7ADSL) was reported to have a high level of Fusarium head blight (FHB) resistance for symptom spread within a spike (Type II) and low deoxynivalenol accumulation in infected kernels (Type III), but a quantitative trait locus (QTL) on chromosome 7A has never been identified from this source. To characterize QTL on chromosome 7A, we developed 191 7A chromosome recombinant inbred lines (7ACRIL) from a cross between Chinese Spring and CS-Sumai 3-7ADSL and evaluated both types of resistance in three greenhouse experiments. Two major QTL with Sumai 3 origin, conditioning both Type II and III resistance, were mapped in the short arm of chromosomes 3B (3BS) and near the centromere of chromosome 7A (7AC). The 3BS QTL corresponds to previously reported Fhb1 from Sumai 3, whereas 7AC QTL, designated as Fhb7AC, is a novel QTL identified from CS-Sumai 3-7ADSL in this study. Fhb7AC explains 22% phenotypic variation for Type II and 24% for Type III resistance. Marker Xwmc17 is the closest marker to Fhb7AC for both types of resistance. Fhb1 and Fhb7AC were additive, and together explained 56% variation for Type II and 41% for Type III resistance and resulted in 66% reduction in FHB severity and 84% reduction in deoxynivalenol (DON) content. Haplotype analysis of Sumai 3 parents revealed that Fhb7AC originated from Funo, an Italian cultivar. Fhb7AC has the potential to be used in improving wheat cultivars for both types of resistance.

A simple Chinese risk score for undiagnosed diabetes

AIMS

A diabetes risk score for screening undiagnosed diabetes was constructed and validated in Chinese adults.

METHODS

Two consecutive population-based diabetes surveys among Chinese adults aged 20-74 years were conducted in 2002 (n = 1986) and 2006 (n = 4336). Demographic and anthropometric measures were collected following similar procedures. Standard 2-h 75-g oral glucose tolerance tests (OGTTs) were performed to diagnose diabetes in both surveys. Fasting capillary plasma glucose (FCG) and glycated haemoglobin (HbA(1c)) were also measured together with the OGTTs on the same day of the 2006 survey. Beta coefficients estimated using logistic regression analysis derived from data of the 2002 survey were used to develop the risk assessment algorithm. The performance of the algorithm was validated in the study population of the 2006 survey.

RESULTS

Of all the variables tested, waist circumference, age and family history of diabetes were significant predictors of diabetes and were used to construct the risk assessment score. The score, ranging from 3 to 32, performed well when applied to the study population of the 2006 survey. The area under the receiver operating characteristic curve was 67.3% (95% CI, 64.9-69.7%) for the score, while it was 76.3% (73.5-79.0%) for FCG alone and 67.8% (64.9-70.8%) for HbA(1c) alone. At a cut-off point of 14, the sensitivity and specificity of the risk score were 84.2% (81.0-87.5%) and 39.8% (38.2-41.3%).

CONCLUSIONS

The risk score based on age, waist circumference and family history of diabetes is efficient as a layperson-oriented diabetes screening tool for health promotion and for population-based screening programmes.